I don’t have a written source for this but we toured the landfill/recycling center in elementary school. Remember distinctly being shown how _only_ the thick necks and bottom portions of number 1 and 2 plastics can be recycled. Plastic bottle caps, as mentioned by the speaker, could not be recycled. It always stuck with me.

Maybe (commercial?) recycling tech has improved to be able to do something with less dense plastic sections but seems diminishing returns. To be fair I’ve seen some cool maker videos of people cutting a bottle into “wire” for 3d printing etc. - but that’s not a commercial/global solution.